The idea is to automatically enable -fobject-code for modules that use
UnboxedTuples, along with all the modules they depend on. When looking
into how to solve this, I was pleased to find that there was already
highly similar logic for enabling code generation when -fno-code is
specified but TemplateHaskell is used.
The state before this patch was that if you used unboxed tuples then you
had to enable `-fobject-code` globally rather than on a per module
basis.